GASTEEOPODA. 307 



Animal •with clavate tentacles ; sole of the foot divided by a 

 longitudinal groove, the side moved, alternatelv in walking; 

 the end of the long muzzle is also frequently applied, as by the 

 looping-snails (Truncatellce), and used to assist in climbing. 



Fig. 135. Cydostoma elegans, from Charlton, Kent. 



Distribution, above 160 species. South Europe ; Africa, 

 Madagascar. The only British species, C. elegans, is found on 

 calcareous soils ; it ranges to the Canaries and Algeria, and 

 occurs fossil in the nevrer Tertiaries. Nearly half the species 

 have the whorls spirally keeled, and have been distinguished 

 under the name TropidopJwra by Troschel. They are found 

 in Madagascar and the adjacent islands and coast of Afiica. 



Fossil, 40 species. Eocene, Europe. 



Sub-genera. Ofojooma, foliaceum, Gray. SJiell sub-globose, 

 umbiHcated ; peristome with an ear-like process covering part 

 of the perforation. Distribution, 15 species. Arabia, Mada- 

 gascar, China, New Ireland. 



Choanopoma, lincina, Pfeiffer. Shell often a little decollated ; 

 peristome usually double, the outer edge angularly expanded. 

 Lincina (labeo), Br., has the last whorl produced. Jamaicia 

 (anomala), C. B. Adams, has the operculum convex. Distribution, 

 70 species. "West Indies, and a few in Tropical America. 



Cistula (fascia). Gray. = Tudora, megacheila. Gray. Shell 

 ovate or elongated, apex usually decollated, peristome free; 

 operculum with a thin shelly outer coat. Chondropoma, semi- 

 labre, Pfr., differs in the operculum being " sub-cartilaginous." 

 Distribution, about YO species. West Indies; Tropical America, 

 8 species. 



Realia, hieroglyphica. Gray. = Hydrocjena (part) Parreyss, 

 Omphalotropis, Pfr. Liarea (Egea), Gray. Bourciera, helicinoe- 

 formis, Pfr. Shell turrcted or turbinate, perforated ; peristome 

 simple, straight or expanded; operculum pauci-spiral, horny. 

 Distribution, 17 species. Canaries, ? Mauritius, Pacific Islands. 

 (Ecuador, Bourciera.) 



Porautias, maculatum, Studcr. Shell slender, transversely 

 striated ; peristome reflected ; operculum cartilaginous, con- 



